1. Field of the Invention
This invention relates generally to improvements in dredging apparatus, and more particularly, but not by way of limitation, to floating dredging apparatus provided with means for self-propulsion and means for pumping large quantities of water and water/solid slurries.
2. Description of the Prior Art
The prior art comprises U.S. Pat. No. 3,962,803, issued to Charles F. O'Brien on June 15, 1976; U.S. Pat. No. 3,738,029, issued to James D. Harmon on June 12, 1973; and U.S. Pat. No. 3,521,387, issued to Norbert V. Degelman on July 21, 1970. All of these patents disclose floating dredging apparatus having articulated boom structures carrying rotating dredging heads on the forward ends thereof. Each of these patents discloses the use of spiral augers on horizontally oriented shafts of relatively small diameter for engaging the bed of a body of water to be dredged. These augers in each case are employed to dislodge the mud and other debris from the bottom and convey such loose debris from either side to the center of the auger where the debris is picked up in a relatively narrow inlet to the suction conduit to be pumped as a water/solid slurry therefrom to some other desired location.
The patents to Harmon and Degelman each disclose the use of radially outwardly extending cutter blades mounted on the outer edges of the auger flights. These cutter blades pass through horizontal cutter bars having corresponding notches formed therein and positioned directly above the axis of rotation of the augers.
In the prior art dredges, the centralized location of the suction opening in the dredging head minimizes the mechanism's ability to efficiently remove material or debris dislodged from the bed of the body of water by the auger blades over the full width of the dredging head since no suction is applied in the area proximate to the outer ends of the auger assembly. Further, the employment of large diameter auger blades on small diameter horizontal shafts provides an excessive amount of space between the horizontal shafts and the cutter bars positioned thereabove for engaging the cutter blades on the outer edges of the auger blades. This latter characteristic of the prior art dredging head structures minimizes the effectiveness of the structures in engaging, chopping and disposing of vegetation, weeds or other fibrous materials encountered by the prior art dredging heads during the dredging operation. The location of the cutter bar directly above the axis of rotation of the auger blades also provides a severe limitation in the prior art devices in that what little chopping or shredding action as may be provided by such apparatus is substantially negated when the counterrotating cutter blades on the auger blades act in concert with the cutter bar to chop up vegetation and weeds, since such chopped vegetation and other fibrous material tends to collect along the forward facing surface of the cutter bar over the full width thereof which, as has been pointed out above, is a substantial distance from the centrally positioned inlet opening of the suction conduit.